Ceramic seal component for gas turbine engine and process of making the same

ABSTRACT

A ceramic brush seal for a gas turbine engine, and a process for manufacturing the seal are provided. In one example, the process includes deinfiltrating an edge of a plurality of plies having a preimpregnated configuration. The edge is defined by a plurality of ceramic fibers extending away from a portion edge of a matrix infiltrated portion of each of the plies. In another example, the process includes masking an edge of a plurality of plies, the edge being defined by a plurality of ceramic fibers extending away from a portion edge of a body portion of each of the plies, and infiltrating the body portion of the plurality of plies with a ceramic matrix slurry. The plies are stacked, formed into a green body and then fired to form the component. The plies may include oxide/oxide woven ceramic fiber plies.

TECHNICAL FIELD

The present application relates to gas turbine engine and itscomponents, and more particularly, but not exclusively, to edge seals ofgas turbine engine components, such as, for example, blades, vanes,airfoils, platforms, end walls, shrouds, and engine bypass walls, andmethods of manufacturing the same.

BACKGROUND

At least some known turbine engines include an air intake portion, acompressor portion, a combustion portion, a turbine portion, and anexhaust portion. Such known turbine engines produce thrust and/orextract energy from a fluid flow by first compressing the intake airwithin the compressor portion. Fuel is added to the compressed air, andthe mixture is combusted in the combustion portion. The resulting hot,high-pressure gas is then expanded through the turbine portion toextract energy therefrom. Management of such hot gas through the engineand out the exhaust portion may require engine components with edgeseals. For example, certain engines have changeable bypassconfigurations that have bypass duct sections disposed near thecombustion portion and in the exhaust portion. These bypass ductsections include metallic brush seals for mechanically sealing slidingairflow and exhaust components during movement between high bypass andlow bypass configurations for selective engine power and fuelconsumption at different operating modes. Current metallic brush sealsexperience high thermal signature, severe creep and oxidation atoperating temperatures approaching 1800 degrees Fahrenheit. Thus, a needexists for improved engine component seals, and methods formanufacturing the same.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments may be better understood with reference to the followingdrawings and description. The components in the figures are notnecessarily to scale. Moreover, in the figures, like-referenced numeralsdesignate corresponding parts throughout the different views.

FIG. 1 depicts an example of a gas turbine engine.

FIG. 2 depicts an example of an engine seal component extending betweenduct sections.

FIGS. 2A-2B depict operation of the engine seal component in FIG. 2.

FIG. 3 is a partial section of the engine seal component in FIG. 2,depicting a stack of plies with a brush seal along a single edge.

FIG. 4 is a partial section of another example of an engine sealcomponent, depicting a stack of plies with a brush seal along multipleedges.

FIG. 5 is a partial section of another example of an engine sealcomponent, depicting an edge seal with bidirectional fibers.

FIG. 6 is a partial section of another example of an engine sealcomponent, depicting a brush seal along a rounded edge.

FIG. 7 is a flow diagram of an example of a process of manufacturing anengine seal component.

FIG. 8 is a flow diagram of an example of a process of manufacturing anengine seal component.

FIG. 9 is a sectional view of another example of an engine sealcomponent.

FIG. 10 depicts another example of an engine seal component.

DETAILED DESCRIPTION

An engine seal component and a process for making an engine sealcomponent are described herein. The engine seal component may be usedfor a variety of applications, as will be described. In one example, theengine seal component is a ceramic brush seal that may be used in achangeable exhaust bypass system, and in particular, the exhaust louverswhen the gas turbine engine is in a bypass mode. The engine sealcomponent may have a rigid body and a flexible fiber brush edge. In oneexample, the engine seal component may extend perpendicular to anopposing counterface surface which may move along the brush fibers. Whenthe engine seal component is constructed from an oxide/oxide CMCmaterial, the oxide/oxide CMC brush seal may have more desirablesurvivability characteristics (for example, low thermal signature)compared to metallic brush seals or SiC/SiC materials at temperatureranging from, for example, about 1800 to 2000° F. The oxide/oxide CMCbrush seal has the potential for lower creep and adhesive wear whencompared to metallic brush seals at temperatures approaching 1800° F.The processes describe various manners to form a ceramic brush sealintegrally with a ceramic seal body, which may be used for any ceramicseal structure.

FIG. 1 is a cross-sectional view of one example of a turbine engine 100.The engine 100 may include one or more of the following: an air intakeportion, a compressor portion 120, a combustion portion 130, a turbineportion 135, and an exhaust portion 140 disposed along a longitudinalaxis CL. The engine 100 may be used in any suitable application, suchas, for example, to produce thrust in aircraft applications, to drive apropeller in aquatic applications, or to drive a generator in energyapplications. In use, air received from the intake portion may becompressed within the compressor portion 120. The compressor portion 120may include a series of bladed disks to form a multi-stage, axialcompressor. The compressed air may be then mixed with fuel and themixture may be burned in combustion portion 130. The combustion portion130 may include any suitable fuel injection and combustion mechanisms.The hot, high-pressure gas may be then passed through the turbineportion 135 to extract energy from the gas, which in turn drives thecompressor portion 120 while discharging thrust out the exhaust portion140.

The exhaust portion 140 of the gas turbine engine 100 may include asegmented exhaust system 150 including a first flow passage 152 and athird stream bypass passage (now referred to as the bypass passage 155)that is used to receive air bypassing the engine core and/or workingfluid from the engine core. In one example, the flow passage 152 may bea fan bypass passage, such as, for example, used in turbofan engines,and/or may be the bypass passage 155 structured to withdraw a portion ofworking fluid from the fan bypass passage. In one example, the thirdstream bypass passage 155 may be used to selectively flow a workingfluid to change the engine cycle of the gas turbine engine 100. Thesetypes of engines may be referred to as adaptive cycle engines. The gasturbine engine 100 may take on a variety of other forms such as aturboprop, turbofan, or turboshaft engine, to set for a few examples.Furthermore, the gas turbine engine may have any number of spools.

The exhaust system 150 may include different operating modes: a highpressure exhaust; a low pressure bypass; and a third outer flow pathwithin the bypass passage 155 that may be opened and closed in responseto operating conditions. The third stream is closed, for example, duringtakeoff, to allow more airflow through the core for increased thrust.The third stream may be opened, for example, during cruising to increasebypass ratio and reduce fuel consumption. The bypass passage 155 for thethird stream may run along the top and bottom of the engine 100. Theflow passage 152 and the bypass passage 155 may be annular inconfiguration, but other configurations are also contemplated. The flowpassage 152 and/or the bypass passage 155 may be segmented such that aplurality of bypass passages is created. In one example, the bypasspassage 155 may be in the exhaust system, as shown, for selective usebetween high bypass and low bypass. In another example, the bypasspassages 155 may withdraw working fluid from a location between theoptional fan 160 (shown in dash lines) and the compressor 120, but otherlocations are also contemplated herein. In other examples, the bypasspassage 155 may withdraw working fluid from a location between stages ofa multi-stage fan, or may be combined in a nozzle with the flow passage152 and engine core flow, but in other embodiments, the working fluidcan be dumped overboard. In one example, the bypass passage 155 may beducted in a non-annular manner.

The bypass passage 155 may include a device or devices useful forclosing off a portion of the bypass passage 155. The device may take avariety of forms and may be deployed using a variety of mechanisms. Inone example, the device may be a combination of a brush seal segmentextending between the top and bottom bypass surfaces of the bypasspassage 155 that move relatively to one another as commanded for closingand opening the bypass passage, as will be described.

FIG. 2 illustrates an engine seal component 210 utilized in the gasturbine engine 100. The engine seal system in FIG. 2 includes a firstsection 220 and a second section 222 that define a passage 223therebetween. The edge seal 212 is shown coupled to the first section220 and extending between the first section 220 and the second section222. The edge seal 212 is supported by the structural body portion 214.The edge seal 212 may extend along the second section 222 in a sealinginterface configuration. In one example, the structural body portion 214of the component 210 may include a plurality of woven ceramic fiberstacked plies, as will be described. The edge seal 212 may includeceramic fibers extending away from the structural body portion 214. Atleast one of the first section with the ceramic seal component and thesecond section are movable relative to one another to define an openconfiguration and a closed configuration of the passage 223, as will bedescribed.

The edge seal 212 of ceramic fibers may inhibit and control fluid flowbetween engine portions or other components. The engine seal component210 may be provided to or along blade platforms, vane end walls, shroudedges, exhaust bypass sections, and other gas turbine engine components.In one example, the engine seal component 210 may be referred to asceramic brush seal. Reference characters A, R, and C define a coordinatesystem representing the respective axial axis, radial axis, andcircumferential axis or directions of the engine seal component 210relative to the longitudinal axis CL of the gas turbine engine of whichit is a part.

In an example, the engine seal component 210 may be include a ceramicstructural body portion 214 along which the edge seal 212 is disposed.The body portion 214 may comprise a ceramic matrix composite (CMC). Inone example, the body portion 214 is formed from one or more pliesstacked. As will be described, the plies may be preimpregnated ceramicpreforms of woven ceramic fiber fabric or dry woven ceramic fiber fabricsubsequently infiltrated by a ceramic matrix slurry. The body portion214 may be formed to any desired shape for an engine environment, notjust the shape illustrated in the figures. The edge seal 212 may includeceramic fibers disposed along one or more edges of the body portion 214to define a brush seal. In one example, the ceramic fibers of the edgeseal 212 may extend away from the body portion 214. Alternatively or inaddition to, the ceramic fibers of the body portion 214 define the edgeseal 212. In one example, ceramic fibers for forming the edge seal maybe ceramic fibers provided in the woven fabric of the plies used in thebody portion 214. Further details as to the body portion and the edgeseal will be described. In one example, the plurality of fibers definingthe edge seal 212 defines a less (for example, at least 95% or less)infiltrated portion than the matrix infiltrated body portion 214. Theceramic fibers defining the edge seal 212 is more flexible (for example,at least twice as flexible) than the body portion 214. In one example,the flexibility of the fiber edge seal maintains the flexibility that ischaracteristic of the ceramic fabric fiber alone.

In one example, the edge seal 212 is provided along the body portion 214to reduce the leakage at the interface between the bypass duct sectionof the bypass passage and exhaust duct section of the flow passage,described previously. Although the edge seal 212 is described herein inthe context of the engine seal component 210 of the bypass passage 155,the edge seal 212 may be applied to any gas turbine engine sealcomponent for which sealing is desired. The engine seal component 210 isshown extending radially from the first section 220 such that the edgeseal 212 is disposed against the second section 222 radially spaced fromthe first section 220. The second section 222 and the first section 220may be formed from an uncoated or coated metal alloy, an organic matrixcomposite (OMC), ceramic matrix composite (CMC) or a monolithic ceramictile to withstand the high temperature environment. The engine sections222, 220 may together define the passage 223. The second section 222 maybe associated with another flow passage, such as the flow passage 152.The edge seal 212 may be oriented perpendicular to the second section222. The use of first and second to describe the engine section are forillustrated purposes, and the edge seal may be oriented in the oppositeupright direction or in lateral directions to extend between a pair ofduct surfaces or other engine sections.

The engine seal component 210 is shown having a rectangularcross-sectional shape along at least one of the axes A, R, C, and insome examples, all of the axes. In one example, the structural bodyportion 214 of the engine seal component 210 includes a rectangularcross-sectional shape along all of the axes. It is contemplated that theengine seal component 210 may have other cross-sectional shapes,including but not limited to rectangular, circular or ellipsoidal, alongany of the axes, such as, for example, to provide an engine componentwith variable thickness for added strength. The body portion 214 of theengine seal component 210 includes a circumferential width sized betweenopposite circumferential edges 230, 232, a radial height sized betweenupper and lower portion edges 240, 242 of the body portion 214 disposedopposite to one another, and a body thickness sized between a downstreamface 250 and an upstream face 252 obverse to the downstream face 250.The height of the edge seal 212, in addition to the radial height of thebody portion 214, will contribute to an overall height of the engineseal component. In one example, the radial height of the engine sealcomponent 210 spans between the engine sections 220, 222.

FIGS. 2A-2B depict a nonlimiting example application of the engine sealcomponent used in the bypass passage (now 155′) of an example of thesegmented exhaust system (now 150′). The engine seal component 210′ isshown as a bypass section 220′ and the duct louvre section 222′ may bemovable relative to one another for selectively closing (FIG. 2A) andopening (FIG. 2B) the bypass passage 155′ defined between the bypassduct section 220′ and another bypass duct section 221′. In one example,the engine seal component 210′ is in a fixed position with the ductsection, and the duct louvre section 222′ is movable in an angled axialdirection. It is contemplated that the duct louvre section 222′ may bein a fixed position, and the engine seal component 210′ is movable insome direction. In one example, the duct louvre section 222′ may definea planar surface, and the edge seal 212′ is disposed in a perpendicularrelationship with the duct louvre section 222′. The duct louvre section222′ is shown coupled to an actuator 259 that is configured to move theduct louvre section. The actuator 259 may be linear actuator including asolenoid and a piston/rod assembly. The actuator may also be configuredfor electrohydraulic or electropneumatic operation. As appreciated byone of ordinary skill, the duct sections 220′ and/or 221′ and/or theengine seal component may be coupled to the actuator 259 for respectivemovement. The actuator 259 is commanded to move between positions basedon a determined output signal from an engine controller (not shown)based on one or more inputs (user or auto selected engine mode and otherengine parameters) and stored maps accessible by the engine controller.

FIG. 2B depicts the duct louvre section 222′ linearly movable along acommon plane relative to the edge seal 212 that is oriented orthogonalrelative to the duct louvre section 222′. When in the openconfiguration, as shown in FIG. 2B, the bypass passage 155′ isconfigured to provide a portion of bypass cooler air (see arrow) to thehotter exhaust gas that is separated from the bypass air by the ductsection 220′. The edge seal is operable to inhibit premature mixing ofthe cooler bypass and hotter exhaust gas. Though the bypass passage 155′is shown in FIG. 2A being closed at a aft portion, other locations forthe device are also contemplated herein. The aft portion in which thedevice is used may either be coincident with the opening at an aft endof the bypass passage, or may be located somewhat upstream from the aftend but still far enough downstream from a forward end of the bypasspassage. In another example, the bypass passage may be closed off at aforward portion of the bypass passage 155′, which is opposite to the aftend shown in FIG. 2A. The forward portion may be either coincident withan opening at the forward end of the bypass passage 155′, or may belocated somewhat upstream from the forward end. In a still furtherembodiment, the bypass passage may be closed at a location intermediatethe forward portion and aft portion.

FIG. 3 depicts the engine seal component 210 formed with a ply lay-upfabrication process, and it may be understood that other fabricationprocesses may also be suitable. The plies may be preimpregnated (alsoreferred to herein as “prepreg”) ceramic preforms of woven ceramicfabric, where the preform or fabric is pre-impregnated with apre-ceramic polymer or ceramic slurry, for example that becomes tackyand allows bonding when the plies are in contact with each other. Inanother example, the plies may be dry woven ceramic fabric configured toreceive a ceramic matrix, rather than being preimpregnated as found inprepreg ceramic preforms. The plies used may have a rectangular sheetconfiguration or be cut into any other shapes, such as, for example,circular or annular, selected to achieve the desired final shape. Forexample, a plurality of plies 300 may be placed in a stackedrelationship. Each of the plies 300 may have a common thickness, radialheight and circumferential width, although it is contemplated that atleast one of the plies 300 may have different thicknesses, heightsand/or widths. Further, one or more of the plies 300 may form a layer,and a plurality of different layers may form the engine seal component.The number of plies 300, plies per layer, and the number of layers forthe engine seal component 210 may be selected based on the particularapplication of the engine seal component and the gas turbine engine.

Each of the plies 300 may be defined by a ply body 302 and a pluralityof fibers 304 extending from the ply body 302. The ply body 302 may bedefined by a matrix infiltrated portion for forming a CMC rigid body andincluding a ceramic fibers (for example, defined by the dashed lines302A) and a ceramic matrix 302B (for example, shown just outside thedashed lines), as understood by one of skill in the art. The fibers 304may include ceramic fibers, and may be woven to include weft fibers andwarp fibers, which is less infiltrated than the ply body 302. One of theweft and warp fibers, shown as the fibers 304, may project from an edge301 of the ply body 302 and is less rigid (or more flexible) than theply body 302. In one example, the fibers 304 may be integral with thefibers that define the CMC rigid body of the ply body 302. In oneexample, the fibers 304 project from the ply body 302 in anunidirectional arrangement, for example, extending in the radialdirection that is generally orthogonal to the circumferential direction(or parallel to the radial axis) that the rigid body 302 is shownextending. In other examples, the fibers in one of the plies may extendat any angle in an unidirectional arrangement, such as for example, 30,45, 60 degrees relative to the radial axis. In another example, adjacentplies may include unidirectional fibers extending at different anglesthan the unidirectional arrangement of the adjacent ply to strengthenthe stacked ply configuration. The fibers 304 are shown extending fromthe ply body 302 by a desirable dimension depending on the applicationand sealing performance sought. In one example, the fibers 304 extendabout 0.25 inches from the bottom of the ply body 302, but may extendany length ranging from 0.010-1.0 inches.

As shown in FIG. 3, the plies 300 when stacked may be oriented such thatthe fibers 304 of each of the plies 300 are in alignment. As shown, theengine seal component 210 may include six oriented plies 300. Thealigned fibers 304 of the plies 300 define the edge seal 212 of theengine seal component 210, and the aligned ply bodies define thestructural body portion 214. The flexibility of the fibers 304 may bedue to the fibers remaining substantially free (95% or more free) ofceramic matrix. In another example, one or more plies 300 of the stackmay be offset relative to others in order to vary the seal edge and itsflexibility.

The engine seal component 210 may include more than one edge seal. FIG.4 illustrates an example of the engine seal component (now referred toas 410) including a first edge seal 412 and a second edge seal 413 alongthe structural body 414 for providing sealing along multiple edges. Theplies include the fibers projecting from the ply body in a bidirectionalarrangement. One portion of the fibers may extend at one angle relativeto the radial axis, with a plurality of first fibers 420 shown parallelto the radial axis to define the first edge seal 412. Another portion ofthe fibers may extend at a different angle relative to the radial axissuch that each portion of the fibers intersect, with a plurality of thesecond fibers 422 shown perpendicular to the radial axis to define thesecond edge seal 414. The intersection of the first and second fibers420, 422 form an intersection angle of about 90 degrees relative to eachother. The engine seal component 410 may include three, four, or moreedge seals depending on the application and shape of the engine sealcomponent.

The ceramic fibers of the engine seal component 210 may include otherintersecting angles in bidirectional arrangements, such as between about30 and about 60 degrees, are contemplated. FIG. 5 shows a bidirectionalarrangement along one of the edge seals 512 of an example of the engineseal component (now referred to as 510). For example, the first fibers520 may extend at about a 45 degree angle along a first axis 524relative to the radial axis RA, and the second fibers 522 may extend ata −45 degree angle along a second axis 526 relative to the radial axisRA. In other examples, it is contemplated that the fibers defining theseal edge may extend in more than two directions (or multidirectional)in predefined directions or in random directions.

The engine seal component 210 may include a non-rectangular body. FIG. 6depicts an example of the engine seal component (now referred to as 610)having a rounded seal edge 612 define by radius R, which may be moresuitable for annular duct passages. The structural body 614 of theengine seal component 610 includes a rounded edge 615, and the seal edge612 extends along the rounded edge. In other words, the ends of thefibers may be configured to form a rounded edge 617. The fibers formingthe seal edge 612 may be unidirectional (as shown), bidirectional, ormultidirectional as described above.

One or more additional components may be integrated into any one of thedisclosed engine seal components. In one example, a component body orfeatures (made either from CMC or non-CMC materials), such as, forexample, attachment features or thermal shields, may be formed prior tointegration or coupling to the edge seal formed by the plies in thelayup fabrication process. In another example, a component body orfeatures may be integrally formed with the edge seal with the same pliesin the layup fabrication process. In another example, the seal componentmay form a partial component for attachment or bonding to bladeplatforms, vane end walls, shroud edges, or other gas turbine enginecomponents.

FIG. 7 illustrates one example of a process of manufacturing, shown as700, one of the disclosed engine seal components utilizing woven,braided or otherwise crossing fibers in prepreg plies. The fibers may beoxide fibers or fiber preforms that are infiltrated with an oxideceramic. One example, of an oxide ceramic textile ply is NEXTEL™ 720,such as the EF-19 cloth (3000 denier, 8HS weave 19 ounces/yard²)provided by 3M. The fiber configuration may be wound ribbons, wovenfabric, or multi-axial woven structures. The fiber configuration mayinclude chopped fibers that are aligned directionally (unidirectional,bidirectional, or multidirectional) or randomly distributed. The matrixmaterial of the composite may be oxide, such as for example, alumina,YAG, mullite, zirconia, zircon, spinel, or cordierite.). The matrixmaterial selected may have suitable properties for the selected fibers,such as, for example, the coefficient of thermal expansion of each maybe matched to reduce thermal strain between the fibers and matrix, whileimproving composite strength and deformation behavior at elevatedtemperature. The oxide ceramic textile ply may be cut into suitablysized pieces for creating the blank from which the brush seal segmentwill be cut.

The number of plies to be used may be determined by the desiredthickness and orientation of the construct after firing or sintering. Inone example, six plies of prepreg oxide ceramic textiles are selected toyield, when stacked, a fired panel thickness ranging from 0.06-0.09 in.After determining the number of plies, the desired length of the edgeseal is predetermined based on the application of the engine sealcomponent and the functionality of the seal. The longer the fibersexposed may yield a more flexible edge seal, while shorter exposedfibers may yield a more durable seal. After determining the length, eachof the prepreg plies is processed to expose a segment of wet infiltratedfibers. For example, the prepreg ply is marked on the polyethylene sheetfrom the bottom edge, such as, for example about 0.3 inches. Along themarking, the polyethylene sheet is cut away on both sides of prepreg plyto expose the wet infiltrated fibers.

At step 702, removal of the ceramic matrix from the wet infiltratedexposed fibers may be performed by a deinfiltration process in one onmore steps. For example, the deinfiltrating step may include using adeinfiltration fluid, such as a solvent or water is configured todissolve the ceramic matrix, such as, for example, ethanol, isopropanolor water. The deinfiltration fluid may be applied to the wet infiltratedexposed fibers by any number of processes, such as by dipping, spraying,or brushing. In one example, a container of solvent having a depth ofsolvent less than the length of exposed fibers is provided, such as, forexample, a depth of 0.1 inches of deinfiltration fluid depth. Thedeinfiltration enhancer, such as an ultrasonic agitator, may be providedwith the solvent container. Alternatively, the fibers may bemechanically agitated by vibration in solvent. The entire edge ofceramic slurry infiltrated exposed fibers of the CMC prepreg sheet maybe flushed by immersion or spraying with solvent for a period of time,leaving the matrix infiltrated fabric portion intact withoutdeinfiltration. After removal, the solvent remaining within the exposeddeinfiltrated fiber edge may be removed by drying in circulating airflowand by contact with an absorbent pad. In other examples, more than onesingle ply may be immersed and flushed in a similar manner.

After the deinfiltration, removal of extraneous fibers from the exposeddeinfiltrated fiber edge may be performed to free the fibers and definethe edge of the ply body. For example, any cross-woven fiber tows may bepulled away and removed from the cloth by a mechanical combing processto inhibit damage done to the remaining fibers. In one example, theextraneous fibers are removed until a length of free vertical fibersremains, such as, for example, about 0.25-inch length.

After removal of extraneous fibers, additional deinfiltration steps,such as described above, may be performed to remove any remainingceramic matrix from the exposed free fibers. In one example, the lengthof exposed free fibers may be dipped in the container of solvent one ormore times (such as, for example, three times) so that substantially nomatrix residue (less than V %) remains on the exposed free fibers ofeach of the prepreg plies.

After the exposed free fiber edge is deinfiltrated, the wet prepregplies with the exposed free fibers may be placed in a stackedrelationship for the desired thickness and orientation (step 704). Inone example, six prepreg plies are layed up in an alternating 0°/90° or±45° orientation. The stacked wet prepreg plies may be layed upon afirst flat plate, such as an aluminum plate, with a release film. Aroller or vertical press apparatus may be used across the stacked pliesto compress the stacked wet prepreg plies and bond them together. Asecond flat plate covered with a release film on the contacting side isplaced over the stacked wet prepreg ply construct.

In the case of silicone-based slurries, the stacked wet prepreg plyconstruct may be then cured into a rigid green body. The rigid greenbody has pre-ceramic polymer matrix material structure that is formedprior to firing. The rigid green body is achieved by applying pressureand/or heat to the stacked construct for forming the rigid green body(step 706). Step 706 is shown dashed as the step may be altered intodrying into the green state for aqueous based slurries. For example, thewet prepreg plies may be cured by heating and/or pressurizing with aheated isostatic hydraulic press, an autoclave or oven vacuum bagging.This curing step may facilitate the evaporation of water in aqueousslurries and light organic compounds in silicone-based slurries based onsiloxanes, silanes and silazanes. The curing time and temperatureprofile may be selected to enable subsequent deinfiltration of thefibers in the green state while maintaining the CMC plate structure. Forexample for silicone-based slurries, the curing temperature may bebetween room temperature or slightly warmer, such as 85° F., to up toabout 400° F., and the curing duration and subsequent cooling durationmay vary depending on the matrix and fiber composition as understood bythose of skill in the art. It is contemplated that certain slurrymixtures may require drying into a green state. For example, water basedslurries, such as but not limited to aqueous colloidal silica orwater-based oxide ceramic may be dried after layup. After drying, thegreen ceramic structure may then go through a firing process, as will bedescribed.

As an optional step, the exposed free fiber edge after molding orpressing into the rigid green body may be further deinfiltrated with thedeinfiltration fluid, such as described above. For example, the exposedfree fiber edge of the rigid green body is flushed or immersed in wateror solvent to dissolve any cured matrix slurry in the region of theexposed free fiber edge and further free the fibers along the edge.Deinfiltration may be enhanced by ultrasonic agitation of the solventduring the flushing and immersion process via mechanical agitation ofthe fibers. One or more immersion/flushing processes may be performeduntil little or no residual matrix remains on the fibers. The as-firedmechanical stiffness of the fibers may be controlled by the diameter ofthe fibers and/or the amount of residual matrix film remaining on thefibers after deinfiltration. Too much residual matrix remaining on thefibers may result in fiber embrittlement after firing.

At step 708, after the curing or drying step or final deinfiltrationsteps, the rigid green body may undergo firing as a freestanding part ina furnace operable in an air atmosphere using a temperature-time profileto enable transformation of the matrix of the rigid green body tomullite (3Al₂O₃-2SiO₂). This step may achieve the removal of anyremaining solvent. For example, the firing temperature may be betweenabout 400° F. to up to about 2200° F., and the duration and subsequentcooling duration may vary depending on the matrix and fiber compositionas understood by those of skill in the art.

After the firing step, the resultant composite may be near final or maybe final into any one of the disclosed engine ceramic seal componentswith the body portion and the brush seal fibers extending beyond theedge portion of the body portion. When near final, additional machiningprocess may be applied to the resultant composite in order to removematerial and form the final shape, size, and configuration of any one ofthe disclosed engine seal components to its desired specifications. Forexample, edges of the resultant composite may be ground or polished,such as with 120 grit or finer mesh SiC or diamond abrasive tooling toform the final ceramic seal component. The resultant composite may befurther finished to receive attachments such as brackets or gaskets toallow secure fastening of the component, provided that it does notadversely affect the structural integrity of the fibers and matrix.

In another example, any one of the disclosed engine seal components maybe undergo a manufacturing process 800 with a positive infiltrationprocess using plies of dry uninfiltrated oxide ceramic fabrics, ratherthan prepreg ceramic preforms. During the infiltration process of theengine seal component, one or more edges of the component is infiltratedless than the remaining body portions of the engine seal component(804). Less infiltration results in less matrix material, which, inturn, may result in the edge being less stiff, that is, more compliantor flexible. For example, the body of the each of the non-impregnatedplies with more slurry infiltration than the edge portion may beinfiltrated with an oxide ceramic slurry. For example, the slurry may beapplied to the plies by immersing the appropriate ends of the plies intoa slurry bath. In addition, ceramic infiltration may be provided using apolymer infiltration and pyrolysis process (PIP), a chemical vaporinfiltration (CVI), a chemical vapor deposition (CVD) process, slurryinfiltration process, and/or melt infiltration (MI) process.

Prior to the infiltrating step, at step 802, the method may include amasking step of one or more plies to inhibit the flow of matrix into themasked free fibers along the one or more edges during the isostaticpressing or vacuum bagging step. The masking applied may be suitablylocated at a certain depth into the ply body or bodies for defining theedge seal length at a desirable length. In one example, the masking mayinclude chemical masking. The chemical masking may include theapplication of a chemical substance soluble in water or organic solvent,such as, for example, a wax, liquid, paste, and/or emulsion, to the freefibers along the one or more edges. The chemical substance used inmasking is operable to withstand green molding temperatures of the oxideCMC (such as, for example, up to 400° F.), yet burn off cleanly duringthe firing step of the oxide CMC, with appropriate attention to burn offwithout causing fiber embrittlement. In one example, the chemical maskis removed during the firing step by being burned off. Careful selectionand application of the chemical mask to the free fibers should inhibitwicking of the chemical mask to regions outside the free fibers.

In another example, alternatively or in addition to the chemical mask,the masking may include a mechanical mask. In one example, themechanical mask may include a mesh screen. The mesh screen may be formedfrom a metallic, polymer or ceramic fiber. The mesh screen includes aporosity sized to receive the free fibers and to inhibit the flow ofmatrix into the masked free fiber region during infiltration. The meshscreen may be placed perpendicular to the fiber direction, with thefiber being inserted or woven into the pores of the mesh. The meshscreen is located at a certain depth into the ply body for defining theedge seal length. The mesh screen may be removed from the fibers afterthe structure is cured or dried into the green body and prior to firing.

In another example, the mechanical mask may include a clampingapparatus. Here, the free fibers may be inserted within the parallelplates of a clamping apparatus. The parallel plates are sized to extendcircumferentially across the fibers and at a suitable edge depth. Theclamping apparatus may be activated, such as, for example, manualcranking, pneumatically, hydraulically, or electrically, to clamp thefree fibers with the paralleled plates with sufficient force untilminimal space between the masked fibers exists to withstand the flow ofmatrix during infiltration. The clamping depth is located at a certaindepth into the ply body for defining the edge seal length The clampingapparatus may be removed from the fibers after the structure is cured ordried into the green body and prior to firing.

Alternatively or in addition to any one of the mechanical masksdisclosed herein, the structure may be oriented upright in a manner suchthat the free fiber edge ends are upward relative to the body to inhibitthe flow of matrix into this region during infiltration due to gravity.Alternatively or in addition to any one of the mechanical masksdisclosed herein, the structure may be pressurized to control of theflow of matrix during infiltration. For example, a positive pressurewith an inert fluid (room air or inert gas), using a compressor system,may be applied along the transition region between the free fibers andthe body to inhibit the flow of matrix into the free fiber region duringinfiltration. In another example, a negative pressure using a vacuumsystem may be applied along the end opposite to the free fiber region todraw the flow of matrix to the body region and inhibit the flow ofmatrix into the free fiber region during infiltration. The pressuredifference created by negative or positive pressure systems may controlthe flow of slurry. The masking from pressure may be removed.

Alternatively or in addition to any one of the chemical and/ormechanical masking disclosed herein, particles, specks, flake, shavings,or pellets of material that are oxidized, etched, dissolved, vaporized,sublimated, or otherwise removed after some stage of compositeprocessing to leave a void. For example, flaked graphite may be insertedalong the transition between the free fibers and the body region and/orwithin the free fiber region. The flaked graphite may be removedmechanically or by oxidation. In another example, a material (e.g.,boron nitride, carbon, molybdenum disulfide) may be applied to the freefiber region to impair the bond between fibers and matrix.

A period of time after the infiltration step may permit the settling andevaporation of the solvents used in the infiltration process. Thesettling time may depend on the composition of the matrix used forinfiltration. The plies may now have tacky surfaces.

The tacky plies with the exposed free fibers may be placed in a stackedrelationship for the desired thickness and orientation (806). In oneexample, six plies are stacked. The plies may be layed upon the firstflat plate with a release film, previously disclosed. The roller orvertical press apparatus may be used across the stacked plies tocompress the stacked plies further to reduce any interior spacingbetween the plies and bond them together. The second flat plate coveredwith a release film on the contacting side is placed over the stackedply construct.

At step 808, the stacked wet ply construct is then cured for forming arigid green body in the case of silicone-based slurries, like in step706, for a suitable temperature and time, and then allowed to cool for asuitable time. Step 808 is shown dashed as the step may be altered intodrying for forming the green body state for a suitable time for aqueousbased slurries. The exposed free fiber edge after molding or pressinginto the rigid green body may be deinfiltrated with the deinfiltrationfluid, such as described above. As described above, when the constructis from a water-based slurry, the process of curing involves drying intoa green state. After the curing step and/or the deinfiltration steps,the green construct may undergo firing (810) as a freestanding part inthe furnace, as described above.

After the firing step, the resultant composite may be near final or maybe final into any one of the disclosed engine seal components with thebody portion and the brush seal fibers extending beyond the edge portionof the body portion. When near final, additional machining process maybe applied to the resultant composite in order to form the final shape,size, and configuration of any one of the disclosed engine sealcomponents to its desired specifications. For example, edges of theresultant composite may be ground or polished, such as with 120 grit orfiner mesh SiC or diamond abrasive tooling to form the final ceramicseal component. The resultant composite may be further finished toreceive attachments such as brackets or gaskets to allow securefastening of the component, provided that it does not adversely affectthe structural integrity of the fibers and matrix.

In another example, both dry oxide ceramic fabric plies and prepregceramic preform plies may be used for forming the engine seal componentusing a similar process as in the process 700. FIG. 9 depicts the engineseal component 900 including first prepreg ceramic preform plies 902,second prepreg infiltrated ceramic preform plies 904, and dryunfiltrated oxide ceramic fabric plies 906 in a stacked relationship.The first prepreg ceramic preform plies 902 form layers alternating withlayers formed by the second prepreg ceramic preform plies 904 and dryoxide ceramic fabric plies 906. The first prepreg ceramic preform plies902 and the second prepreg ceramic preform plies 904 may be sizeddifferently. In one example, the first prepreg ceramic preform plies 902are sized to extend beyond the second prepreg ceramic preform plies 904.Extending from the spaces created by size difference between the firstand second prepreg ceramic preform plies 902, 904 are the dry oxideceramic fabric plies 906 which are adjacent the preform plies 904. Thedry oxide ceramic fabric plies 906 are sized to extend beyond the firstprepreg ceramic preform plies 902. In one example, the dry oxide ceramicfabric plies 906 includes a first portion overlapping the first prepregceramic preform plies 902, and a second portion extending beyond theplies 902 for defining the free fiber edge. In one example, the firstportion may abut or be engaged with the edge of the prepreg plies 904.In another example, the first portion may overlap the edge of theprepreg plies 904, or a gap may exists between the two plies. Theprepreg plies 902, 904 may define the more rigid structural portion ofthe engine component. The prepreg plies 902, 904 may secure dry plies906 sandwiched in alternate layers. In another example, the firstprefrom plies 902 are sized to extend to the tip of the fabric plies 906and form a portion of the seal edge after deinfiltration. During theforming process, matrix from the prepreg plies may wick or infiltratethe first portion of the dry plies. Masking, such as described above,may be used to prevent infiltration into the second portion.Deinfiltration processes may be utilized to rid the second portion ofany matrix. With the use of the combination of plies, lessdeinfiltration may be needed, which may show an improvement in the speedand costs of manufacturing.

As described above, extraneous fibers may be removed from the exposedfiber edge to free the fibers along the seal edge. In another example,the seal edge 1002 of the engine seal component 1000 may be configuredas a drape end 1004, as shown in FIG. 10. As an optional step in any oneof the processes 700 or 800, the ply end may sewn up with a threading toform the drape end. To this end, a portion or none of the cross-wovenfiber tows may be removed. Instead, the fabric end is sewn up with athreading, such as a Nextel thread, to prevent unraveling of the freefibers. This may occur prior to layup or stacking step, deinfiltrationstep, or infiltration step. This configuration may provide the engineseal component with a flexible fabric drape seal extending from thestructural seal body rather than free brush fibers. In one example, theend cross-woven fiber tows remain in place and a segment of cross-wovenfiber tows immediately adjacent to the remaining end cross-woven fibertows are removed. This configuration may provide a seal having the drapeend 1004 with an exposed fiber segment 1006, that may provide additionalflexibility to the drape seal. When less adjacent tows are moved and/ormore threading is sewn, a smaller portion of the free fibers are exposedand a more solid drape end may be formed. In one example, the drape endis in fully woven fabric.

Although the processes disclosed herein have been described withoxide/oxide CMC's, one of ordinary skill in the art may make suitablemodifications to the process steps for other CMC composites, such asSiC/SiC composites. When the component is constructed from anoxide/oxide CMC material, the oxide/oxide CMC brush seal may have alower thermal signature compared to metallic brush seals or SiC/SiCcomponents at temperature ranging from about 1800 to 2000° F. Theoxide/oxide CMC brush seal may have the potential for lower creep andadhesive wear when compared to metallic brush seals or SiC/SiC materialsat temperature ranging from about 1800 to 2000° F. The processesdescribe various manners to form a ceramic brush fiber seal integrallywith a ceramic seal body.

To clarify the use of and to hereby provide notice to the public, thephrases “at least one of <A>, <B>, . . . and <N>” or “at least one of<A>, <B>, <N>, or combinations thereof” or “<A>, <B>, . . . and/or <N>”are defined by the Applicant in the broadest sense, superseding anyother implied definitions hereinbefore or hereinafter unless expresslyasserted by the Applicant to the contrary, to mean one or more elementsselected from the group comprising A, B, . . . and N. In other words,the phrases mean any combination of one or more of the elements A, B, .. . or N including any one element alone or the one element incombination with one or more of the other elements which may alsoinclude, in combination, additional elements not listed.

While various embodiments have been described, it will be apparent tothose of ordinary skill in the art that many more embodiments andimplementations are possible. Accordingly, the embodiments describedherein are examples, not the only possible embodiments andimplementations.

Furthermore, the advantages described above are not necessarily the onlyadvantages, and it is not necessarily expected that all of the describedadvantages will be achieved with every embodiment.

The subject-matter of the disclosure may also relate, among others, tothe following aspects:

1. A process of manufacturing a ceramic seal component, comprising:deinfiltrating an edge of respective preimpregnated plies such that thedeinfiltrated edge is defined by a plurality of ceramic fibers extendingaway from a portion edge of a matrix infiltrated portion of each of theplies, the plurality of ceramic fibers defining a less infiltratedportion than the matrix infiltrated portion; placing the plies with thedeinfiltrated edge in a stacked relationship, and orienting thedeinfiltrated edge of each of the plies in alignment with each other todefine a stacked structure; and firing the stacked structure to form aceramic seal component having a flexible seal edge formed by theplurality of ceramic fibers projecting from a rigid body formed by thematrix infiltrated portion of each of the plies.

2. The process of aspect 1, wherein the deinfiltrating comprisesflushing at least a portion of the edge of each of the plies withdeinfiltration fluid.

3. The process of any one of aspects 1-2, further comprising removing atleast a portion of extraneous fibers from the deinfiltrated edge tofurther free the ceramic fibers.

4. The process of aspect 3, wherein the removing further comprisesfreeing the ceramic fibers of the deinfiltrated edge to a predeterminedlength along the edge.

5. The process of any one of aspects 1-4, further comprising threadingthe edge with a thread member to define a drape end.

6. The process of any one of aspects 1-5, further comprising applyingpressure and heat to the oriented plies in the stacked relationship toform a rigid green body; and deinfiltrating the edge including theplurality of ceramic fibers after the forming of the rigid green bodyand prior to the firing.

7. The process of any one of aspects 1-6, wherein a layer of the pliesstacked includes an uninfiltrated ply adjacent an infiltrated ply.

8. The process of any one of aspects 1-7, wherein the plies include awoven oxide ceramic fiber fabric, the ceramic fibers include oxideceramic fibers, and the matrix infiltrated portion of each of the pliesincludes an oxide ceramic matrix.

9. A process of manufacturing a ceramic seal component, comprising:masking an edge of each of a plurality of plies, the edge being definedby a plurality of ceramic fibers extending away from a portion edge of abody portion of each of the plies; infiltrating the body portion of theplurality of plies with the masked edge with a ceramic matrix slurry,the masked edge with the plurality of ceramic fibers defining a lessinfiltrated portion than the body portion; placing the plurality ofplies with the infiltrated body portion and masked edge in a stackedrelationship, and orienting the masked edge of each of the plies inalignment with each other to define a stacked structure; and firing thestacked structure to form a seal component having a flexible seal edgeformed by the plurality of ceramic fibers projecting from a rigid bodyformed by the infiltrated body portion of each of the plies.

10. The process of aspect 9, wherein the masking step comprisesmechanically masking.

11. The process of aspect 10, wherein the mechanically masking includesinserting the plurality of ceramic fibers extending away from the edgeinto pores of a mesh screen prior to the infiltrating, and removing themesh screen from the plurality of ceramic fibers after the applying.

12. The process of any one of aspects 10-11, wherein the mechanicallymasking includes clamping the plurality of ceramic fibers extending awayfrom the edge within a clamping device prior to the infiltrating, andremoving the clamping device from the plurality of ceramic fibers afterthe applying.

13. The process of any one of aspects 10-12, wherein the mechanicallymasking includes positioning the edge upright relative to the bodyportion.

14 The process of any one of aspects 9-13, wherein the masking stepcomprises chemical masking with a chemical substance configured towithstand conditions from the applying pressure and heat and to burn offduring the firing.

15. The process of any one of aspects 9-14, wherein the plies include awoven oxide ceramic fiber fabric, the ceramic fibers include oxideceramic fibers, and the matrix infiltrated portion of each of the pliesincludes an oxide ceramic matrix.

16. An engine seal system, comprising: a first section and a secondsection defining a passage; and a ceramic seal component coupled to thefirst section and extending between the first section and the secondsection, the ceramic seal component comprising a structural body portionand an edge seal, wherein the edge seal extends along the secondsection, the structural body portion comprising a plurality ofoxide/oxide woven ceramic fiber stacked plies, the edge seal comprisingoxide ceramic fibers extending away from the structural body portion,the edge seal being more flexible and less infiltrated with oxideceramic matrix slurry than the structural body, wherein at least one ofthe first section with the ceramic seal component and the second sectionare movable relative to one another to define an open configuration anda closed configuration of the passage.

17. The system of aspect 16, wherein the plurality of oxide ceramicfibers extends away from an edge of the structural body portion in aunidirectional arrangement.

18. The system of aspect 16, wherein the plurality of oxide ceramicfibers extends away from an edge of the structural body portion in abidirectional arrangement.

19. The system of aspect 18, wherein the plurality of oxide ceramicfibers having the bidirectional arrangement comprises a first fiberintersecting a second fiber at an angle of up to 90 degrees.

20. The system of any one of aspects 16-19, wherein ends of theplurality of oxide ceramic fibers form a rounded edge.

What is claimed is:
 1. A process of manufacturing a ceramic sealcomponent, comprising: deinfiltrating an edge of respectivepreimpregnated plies such that the deinfiltrated edge is defined by aplurality of ceramic fibers extending away from a portion edge of amatrix infiltrated portion of each of the plies, the plurality ofceramic fibers defining a less infiltrated portion than the matrixinfiltrated portion; placing the plies with the deinfiltrated edge in astacked relationship, and orienting the deinfiltrated edge of each ofthe plies in alignment with each other to define a stacked structure;and firing the stacked structure to form a ceramic seal component havinga flexible seal edge formed by the plurality of ceramic fibersprojecting from a rigid body formed by the matrix infiltrated portion ofeach of the plies.
 2. The process of claim 1, wherein the deinfiltratingcomprises flushing at least a portion of the edge of each of the plieswith deinfiltration fluid.
 3. The process of claim 1, further comprisingremoving at least a portion of extraneous fibers from the deinfiltratededge to further free the ceramic fibers.
 4. The process of claim 3,wherein the removing further comprises freeing the ceramic fibers of thedeinfiltrated edge to a predetermined length along the edge.
 5. Theprocess of claim 1, further comprising threading the edge with a threadmember to define a drape end.
 6. The process of claim 1, furthercomprising applying pressure and heat to the oriented plies in thestacked relationship to form a rigid green body; and deinfiltrating theedge including the plurality of ceramic fibers after the forming of therigid green body and prior to the firing.
 7. The process of claim 1,wherein a layer of the plies stacked includes an uninfiltrated plyadjacent an infiltrated ply.
 8. The process of claim 1, wherein theplies include a woven oxide ceramic fiber fabric, the ceramic fibersinclude oxide ceramic fibers, and the matrix infiltrated portion of eachof the plies includes an oxide ceramic matrix.
 9. A process ofmanufacturing a ceramic seal component, comprising: masking an edge ofeach of a plurality of plies, the edge being defined by a plurality ofceramic fibers extending away from a portion edge of a body portion ofeach of the plies; infiltrating the body portion of the plurality ofplies with the masked edge with a ceramic matrix slurry, the masked edgewith the plurality of ceramic fibers defining a less infiltrated portionthan the body portion; placing the plurality of plies with theinfiltrated body portion and masked edge in a stacked relationship, andorienting the masked edge of each of the plies in alignment with eachother to define a stacked structure; and firing the stacked structure toform a seal component having a flexible seal edge formed by theplurality of ceramic fibers projecting from a rigid body formed by theinfiltrated body portion of each of the plies.
 10. The process of claim9, wherein the masking step comprises mechanically masking.
 11. Theprocess of claim 10, wherein the mechanically masking includes insertingthe plurality of ceramic fibers extending away from the edge into poresof a mesh screen prior to the infiltrating, and removing the mesh screenfrom the plurality of ceramic fibers after the applying.
 12. The processof claim 10, wherein the mechanically masking includes clamping theplurality of ceramic fibers extending away from the edge within aclamping device prior to the infiltrating, and removing the clampingdevice from the plurality of ceramic fibers after the applying.
 13. Theprocess of claim 10, wherein the mechanically masking includespositioning the edge upright relative to the body portion.
 14. Theprocess of claim 9, wherein the masking step comprises chemical maskingwith a chemical substance configured to withstand conditions from theapplying pressure and heat and to burn off during the firing.
 15. Theprocess of claim 9, wherein the plies include a woven oxide ceramicfiber fabric, the ceramic fibers include oxide ceramic fibers, and thematrix infiltrated portion of each of the plies includes an oxideceramic matrix.
 16. An engine seal system, comprising: a first sectionand a second section defining a passage; and a ceramic seal componentcoupled to the first section and extending between the first section andthe second section, the ceramic seal component comprising a structuralbody portion and an edge seal, wherein the edge seal extends along thesecond section, the structural body portion comprising a plurality ofoxide/oxide woven ceramic fiber stacked plies, the edge seal comprisingoxide ceramic fibers extending away from the structural body portion,the edge seal being more flexible and less infiltrated with oxideceramic matrix slurry than the structural body, wherein at least one ofthe first section with the ceramic seal component and the second sectionare movable relative to one another to define an open configuration anda closed configuration of the passage.
 17. The system of claim 16,wherein the plurality of oxide ceramic fibers extends away from an edgeof the structural body portion in a unidirectional arrangement.
 18. Thesystem of claim 16, wherein the plurality of oxide ceramic fibersextends away from an edge of the structural body portion in abidirectional arrangement.
 19. The system of claim 18, wherein theplurality of oxide ceramic fibers having the bidirectional arrangementcomprises a first fiber intersecting a second fiber at an angle of up to90 degrees.
 20. The system of claim 16, wherein ends of the plurality ofoxide ceramic fibers form a rounded edge.